94 caprice 9c1 transmission problem

4l60e auto.car shifts firm and positive through all gears,fluid and filter is new,under HEAVY to FULL throttle it acts as though its trying to downshift when speeds are too high to do so,if you hit passing gear under light to moderate acceleration it kicks down and shifts proper. car has 160,k runs like new,except this issue, acts the same in drive or overdrive.could it be the manifold pressure swith?

4l60e auto.car shifts firm and positive through all gears,fluid and filter is new,under HEAVY to FULL throttle it acts as though its trying to downshift when speeds are too high to do so,if you hit passing gear under light to moderate acceleration it kicks down and shifts proper. car has 160,k runs like new,except this issue, acts the same in drive or overdrive.could it be the manifold pressure swith?
if the downshifting is too soon could be tps. if you put pedal to the metal or 3/4 down it will downshift. above 110mph i don't know.

I'd have to hack the program again, but as I recall the TCC can release at WOT but OD does not drop above 92-ish MPH.

I'd have to hack the program...

A real hacker you is lol

I'm guessing your working with a blackmarket AKM cable too, you badass :)